The choice depends on your height & body type. If you're 6'+ and thin build like I am, I'll take the E+ middle every time. Otherwise, the E- aisle is appealing. I did take the E- aisle on a pre-PS JFK-SFO flight on a 757 last year and was miserable. I don't think I'll do that again.
Also, the fact that this is an Airbus with the extra width makes it an easier choice for me.